Earlier this year, I appeared on the BBC and was asked a question by Laura Kuenssberg that I hadn’t anticipated: did I believe there’s a problem with mental health overdiagnosis?

I gave a simple answer, that yes, I did think there was overdiagnosis, that too many people were being written off, and too many people weren’t getting the support they needed.

I was then deluged with messages and emails of both enthusiastic agreement and visceral disagreement – including from mental health clinicians on both sides of the argument. One angry patient messaged to say: “Far from overdiagnosis, I can’t even get an appointment to get a diagnosis.” The worst thing was that I agreed with them, but I had failed to capture the complexity of this problem.

The truth is there has been a massive growth in mental health and behavioural issues and there isn’t a consensus within the mental health clinical community on what is driving it. There was an almost 50% increase in mental health problems among adults between 1993 and 2023. Mental health referrals for children and young people increased by about 50% in just two years during the pandemic. And 13 times more people are waiting for an autism assessment today compared with 2019.

Whether this is because people are more open about their mental health, there is growing awareness of these conditions, these are consequences of the pandemic or there have been other drivers, we have got to get to the bottom of the causes of this.

Because services are not keeping up.

As the Darzi investigation uncovered, around 109,000 young people and children were waiting more than a year for their first appointment with a mental health specialist. This is despite an increase in spending on mental health services by more than 50% since 2019.

I know from the personal experience of some of my nearest and dearest the pain this is causing. One has attempted to take their own life after struggling to get any mental health support. A family member has suffered from the shortages of medication for attention deficit hyperactivity disorder, seriously affecting his mental health. At the same time, I have seen the transformational impact an early autism diagnosis can have for the support and education a child receives.

It was following my own episode with foot-in-mouth syndrome on live television that I decided this issue was too important to be left unresolved and required a proper evidence base. That’s why my department has asked the esteemed Prof Peter Fonagy, along with Sir Simon Wessely and Prof Gillian Baird, to lead a review into the prevalence and support for mental health conditions, autism and ADHD. The review brings together some of the most respected researchers, clinicians and voluntary organisations in the country, alongside people with lived experience.

I’ve asked them to weigh the data, examine the quality of evidence, diagnose the problem and offer recommendations on how the NHS can meet the needs of all.

I’m delighted that this review is backed by Mind, the Mental Health Foundation, the National Autistic Society, the Royal College of Psychiatrists and Anne Longfield, the former children’s commissioner for England. All can see the current system is failing, and are motivated by the need to fix it. As Dr Sarah Hughes, Mind’s chief executive, said: “This is a huge opportunity to really understand what is driving increasing levels of mental illness, especially among our young people.”

I’m not waiting for the review to conclude to begin turning around our mental health services. Since the election, we’ve recruited more than 7,000 extra mental health staff, we’ve increased the number of NHS Talking Therapies sessions, we’re building new mental health emergency departments for those reaching crisis point, and we’ve now got mental health support in almost half the schools in UK, because prevention is better than cure.

But there’s a lot more to do. And to get the prescription right, we first need to accurately diagnose what is causing the surge in mental ill health. That is how we will ensure that everyone gets the support they need, when they need it.